Problem....

Hello guys/girls.. got a mk3 mondeo and got a problem..started a couple of weeks ago and only happened twice since..what it is..you drive the car stop do what you've got to do then back into the car turn the key tries to turn over get a couple of revs then dies...leave it for about 5-10 mins and it starts as if nothing has happened..by the way its 2ltr petrol zetec...could it be cam shaft sensor ?..fuel pump ?..thanks for you're help..

thats what i'm thinking along them lines steve..any way..since it last happened i've not had any trouble(touch wood) i can hear the fuel being primed on the turn of the key so i don't think its the fuel pump..so at the mo i'm at a loss..thanks for you're answers guys...